Hydrogen production from an integrated coker gasifier system

ABSTRACT

HIGH CONRADSON CARBON FEEDS ARE COKED TO LAY DOWN EXTENSIVE CARBON DEPOSIT ON A GASIFICATION CATALYST. THE COKED CATALYST IS THEN STEAM GASIFIED TO PRODUCE HYDROGEN. PART OF THE COKED CATALYST MAY BE PARTIALLY BURNED TO PRODUCE HEAT FOR THE COKING STEP.   D R A W I N G

April 10, 1973 c, RUN JR ET AL 3,726,791

HYDROGEN PRODUCTION FROM AN INTEGRATED COKER GASIFIER SYSTEM Filed July16, 1970 2 E w 5 E (D i 2 u I l (2 :2 Q M E" I l or n: 2 2 '2 (.15 U D 5m :1 LIJ 5 3 v 8 n: I l

' g ml l l 5 E *5 g ll- (I) 5 O D E U 0 LL! X 0 U l (I) 0 QB l 8 r 2 8 18 "H s E I D O. I El (9 v; 3% N x O 5 m INVENTORS c. N. K|MBERL|N,JR.

GLEN r? HAMNER BY 1m, .3 11%,. Q1. ATTORNEY United States Patent O Ser.No. 55,443

Int. Cl. Cg 9/28 US. Cl. 208-127 12 Claims ABSTRACT OF THE DISCLOSUREHigh Conradson carbon feeds are coked to lay down extensive carbondeposit on a gasification catalyst. The coked catalyst is then steamgasifled to produce hydrogen. Part of the coked catalyst may bepartially burned to produce heat for the coking step.

RELATED APPLICATIONS This is a continuation-in-part of application Ser.No. 802,800 filed Feb. 27, 1969 and now abandoned.

BACKGROUND OF THE INVENTION The economic utilization of high Conradsoncarbon byproducts obtained in petroleum processes such as catalyticcracking, vacuum distillation, etc, has long been a problem in thepetroleum industry. E. W. Riblett (US. Pat. 2,600,430) proposed firstcoking at high temperatures, and then utilizing the coke produced eitherin an oil cracking reactor or in a noncatalytic gasification reactor.The cracked product from the oil cracking reactor or the synthesis gasproduced from the gasification was recovered for use as fuel or for usein further refining processes. The primary obstacle in such processes isthe extremely high temperature that must be maintained. In order tomaintain the temperature, heat had to be added into the reactors. Such arequirement is very costly and makes such processes noneconomical.

Another problem in the petroleum industry has been the need to obtainhydrogen for use in the refining processes. Therefore, a process whichcould economically utilize high Conradson carbon by-products to producehyindustry.

SUMMARY OF THE INVENTION It has now been found that high Conradsoncarbon feeds can be economically employed in low temperature, integratedcoking/ catalytic gasification process to produce hydrogen. Morespecifically, it has been found that by depositing metal supportedgasification catalyst in a coking reactor to be contacted with the cokeproduced in the coking reactor, and then transferring the cokegasification catalyst to a steam gasification reactor, hydrogen may beeconomically produced. Most specifically, it has been found thatnickel-uranium or thorium deposited on a bauxite gasification catalystdeposited in a fluid coking reactor to be contacted with the cokeproduced in the fluid coking reactor, and transferring the cokednickeluranium or thorium deposited on a bauxite gasification catalyst toa burner reactor to provide heat for the coking reactor and to raise thetemperature of the coked gasification catalyst to the desiredtemperature, and then transferring the heated coked gasificationcatalyst to the gasification reactor can economically produce hydrogen.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing is a schematicrepresentation of the preferred embodiment of the invention.

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Referring now to the drawing, a high Conradson carbon and preferablyhigh metal content feedstock is introduced into the upper portion ofcoking zone 1 by line 2 onto a fluidized bed 3 maintained at atemperature of 850l050 F., and a pressure ranging from 5 to p.s.i.g. Thefluid bed preferably consists of particulate catalyst particles whichmay be any type of gasification catalyst known in the art, but which ispreferably a Group VIII metal oxide, such as nickel or cobalt oxide,deposited on a suitable support. The support may contain from 0.5 to 5percent of the active catalyst. The catalytic support may be eithergamma alumina, bauxite, or activated clay. Other suitable catalystsinclude metal oxides of Group VII-B such as manganese oxide, Group V-Bsuch as vanadium oxide, rare earths, thorium oxide and U 0 combined ornot with the above metal oxides on such basis.

The feed is prferably a low value, high-boiling residuum of about 10 to+20 A'P I gravity, about 5-50 wt. percent or higher Conradson carbon,containing from 50 to 1000 ppm. of metal, such as nickel, vanadium andthe like and boiling above about 9001200 F. However, any stock having aConradson carbon above 5 may be used. The particules of catalyst aremaintained as a fluid bed by the upward passage of a fluidizing gas suchas steam which enters the lower portion of coking zone 1 through line 4.The contact of the heavy feed and the catalyst results in the feed beingconverted to lower boiling vaporous hydrocarbons and to coke which isdeposited on the gasification actalyst along with the metal in the feed.The vaporous hydrocarbons and steam are removed through line 5 while thefluidized catalyst particles descend in bed 3 and are Withdrawn from thelower portion of coking zone 1 through line 8 and are introduced intocoke burner 9 wherein part of the coke from the gasification catalyst isoxidized to produce carbon oxide by means of an oxygen-containing gassuch as air introduced through line 10 with a resultant rise intemperature of the catalyst-coke mixture to at least 1250 F. and underpreferrd operating conditions of 13504500 F. The temperature at whichthe reaction in the oxidation zone is effected may be controlled byregulating the quantity of oxygen-containing gas, by regulating thetemperature of the oxygen-containing gas, and by regulating the amountof coke present in the coke burner. It is also controlled by the amountof metal deposited on the catalyst which in turn is determined by themetal content of the feed. The more common of the metallic contaminantsare nickel and vanadium, often existing in concentration in excess of 50ppm, although other metals including iron, copper, etc., may be present.These metals may exist within the feed in a variety of compositions suchas porphyrin structure. Additional catalytic metal components may beadded with the feed as metal oxides or sulfides or as soluble salts.Usually, however, they are present in the form of high molecular weightorgano-metallic compounds, including metal porphyrins and variousderivatives thereof. The presence of these metals on the catalyst,particularly nickel, have an additional catalytic effect which in turnenables the gasification step to be carried out at lower temperatures.The amount of oxygen in the oxygen-containing gas may be regulated byblending inert gaseous material, such as steam, nitrogen or flue gas,with the air or oxygen used. If desired, the amount of coke burned maybe controlled by the introduction of liquid or gaseous fuel to be burnedinstead of the coke.

A portion of the heated catalyst and coke in burner 9 may be returned tocoking zone 1 by line 6 to control the temperature therein. Nitrogen,excess air, oxygen and other gases are removed from coke burner 9through line 11. Care must be made to insure that all nitrogen isremoved since it is highly desirable to prevent the introduction of anynitrogen into the gasifier 7. Therefore it should be removed prior tothe introduction of the cokedmetal contaminated catalyst to thegasifier. The presence of nitrogen will contaminate the hydrogen gasproduct, requiring an extra costly step for its removal.

It is also highly important that the production of methane in thegasification reactor be as low as possible. The production of methaneresults in less hydrogen being produced, because the hydrogen is beingused to produce the methane. Preferably, there should be less than 2 molpercent on a dry basis of methane produced.

The remaining heated catalyst and coke particles are withdrawn fromburner 9 through line 12 and supplied to the top of gasifier 7 with theparticles dropped into fluidized bed 13 supplying heat thereto andmaintaining the temperature therein between 1200 and 1450" F. However,whenever desired, co-ked catalyst may be with- 4 ing operation. Thecoked catalyst would then be removed from the coking drum andtransferred to a gasifier.

The following examples are presented as specific illus trations of thepresent invention. All quantities are expressed in the specification andclaims on a weight basis unless stated otherwise.

EXAMPLE 1 NiU/ Ni-Th/ Ni-U/ Bauxbauxitc 1 bauxite 2 a-Algoa 1 F8203 ite3 CKA1203 Catalyst:

Weig percent c 13. 5 14.3 21. 6 15. 13. 3 10.1 Gasification temperatur1,360 l, 355 1, 360 1, 350 1, 350 1, 345 Gas rate, s.c.v.ll

minutes 0. 09 0. 009 4 0. 047. 0. 066 0. 047 4 0. 034 Gas composition,molecular percent Hr 61. 5 59. 4 57. 1 65. 8 63. 5 62. 1 00... 11.5 13.219.0 4.9 7.6 17.4 CO2--- 25. 6 26. 0 21. 6 27. 6 26. 6 18. 4 CH4 1.4 1.42.3 1.7 2.3 2. 1

1 Ni plus U concentration of 1.5 and 0.5 weight percent, respectively.

2 Ni plus Th concentration of 1.5 and 0.5 weight percent, respectively.

I No metal added to the base material.

4 Gas rate obtained for 60 minutes.

drawn through line 14 in order to prevent too high a buildup of metalsin the system. The reactions in the gasifier may be effected atsubstantially atmospheric pressure or pressures up to 150 p.s.i.g., ifdesired, although it is preferable to operate at substantiallyatmospheric pressure in order to prevent the saturating effect ofhydrogen on any volatile conversion products in the gasifier. Steam fromfiuidizing bed 13 and for gasifying the coke on the catalyst isintroduced through lines 17 and 18.

Hydrogen-producing reactions are not simple and may require particularconditions to be maintained in the gasifier in order to produce the mostdesirable products. The various reactions between water and carbonproduce principally hydrogen, carbon dioxide and carbon monoxide, withformation of minor amounts of methane and possibly heavier hydrocarbons.Each of the reactions operates independently with regard to theequilibrium established at each temperature. However, the reactions areinterrelated in that variations of the equilibrium between products andreactants in one reaction will change the concentrations of reactantsand products of the other reaction. The gas composition leaving vessel 7through line has the following typical composition by mol percent on adry basis:

The solid catalyst particles which are coke depleted descend to thelower portion of gasifying zone 7 and are Withdrawn through line 19 andreturned to coking zone 1 through line 20.

From the above description it is evident that a process has beenprovided for economically coking a heavy residual or other oil have aConradson carbon above 5 whereby coke is laid down on the gasificationcatalyst and used to produce hydrogen by reaction with steam.

While the above process has been described in connection with a fluidtype process, it is obvious, of course, that other techniques may beused. For example, the coke may be laid down on the catalyst in adelayed cok- The above data show that gasification rates are increasedtwo-fold with metal promoters on bauxite as the base material atconditions evaluated. The bauxite base is four-fold better than the lowsurface area base such as tat-alumina. Metals addition also increasesthe gasification rate when using the low surface area on alumina base.Lower methane formation is indicated for the metalbauxite catalyst. Itis desirable to produce minimum methane 2%) since it becomes an impurityin the hydrogen stream after the CO shift reaction and eventual COremoval operation.

[EXAMPLE 2 Fluid coke deposition on a catalytic support, partialcombustion to raise the temperature of the catalytic solids plus carbonabove the desired steam gasification temperature and finally steamgasification of carbon from the catalytic support as described in thedrawing were carried out to demonstrate the process for hydrogenmanufacture. For the fluid process the particle size of the catalyst wasadjusted to a -200 mesh. Bachaquero residuum feed used in Example 1 wascontacted with catalytic fluid solids consisting of Ni-U/bauxite at 950F. until a carbon level of 12.5 wt. percent was realized. The catalyticsolids plus carbon was burned at 1500 F. with controlled quantity of airsuch that about 20% of the carbon was consumed. The catalytic supportplus 10 wt. percent carbon was then contacted with steam at 1400" F.such that about 30% of the available carbon was gasified. Synthesis gasfor the unburned and burned Ni-U/bauXite-carbon mixtures when gasifyingat 1400 F. are shown below.

N i-U/Bauzfdte carbon Although lower gasification rates were obtainedwith the preoxidized catalytic-carbon mixture, the hydrogenconcentration is considerably better with one-half to onethird lessmethane impurity as that obtained for the freshly deposited carbonbefore the burner operation. After conventional water-gas shift of theCO and coupled with CO removal, a 95% hydrogen stream is indicated forthe integrated process.

EXAMPLE 3 Fluid operation was also carried out whereby carbon fromBachaquero residuum feed employed in Example 1 was deposited on MnOsolids of 1002'O0 mesh at 950 P. such that a carbon level of 14.6 wt.percent was realized. The MnO-carbon mixture was then steam gasified at1400 F. Ga'sification rate was equivalent to that obtained with thepreoxidized NiU/bauxite-carbon mixture shown in Example 2. A yield of0.055 s.c.f. 15 min. of synthesis gas from a 10 gram charge (catalystplus 14.6 wt. percent carbon) was obtained which had the followingcomposition, mol. percent on dry gas:

H2 65.9 co 7.1 co 24.9 c 2.1

EXAMPLE 4 A Bachaquero residuum having an API gravity of 13.5 aConradson carbon of 11% and having an initial boiling point of 450 F.was contacted with manganese oxide as catalyst under delayed coking typeoperations at a temperature of 950 P. such that 15 wt. percent coke wasdeposited on the catalyst. The catalyst was then steamed at 1300 -F. forfifteen minutes with excess steam so that about 50% of the availablecarbon was gasified. A yield of 0.132 s.c.f. of synthesis gas from a tengram charge (catalyst plus 15 wt. percent carbon) was obtained which hadthe following composition in mol. percent on dry gas:

The nature of the present invention having thus been fully described andillustrated and specific examples of the same given, What is claimed asnew, useful, and unobvious and desired to be secured by Letters Patentis:

1. An integrated coking and steam gasification process for producingliquid hydrocarbon products and a low methane, hydrogen rich gaseousstream which comprises:

(a) treating a carbonaceous material having a Conradson carbon residueof at least 5 wt. percent and a supported Group V-B, VII-B or VIII metaloxide steam gasification catalyst in a coking zone operating at cokingconditions in the absence of additional hydrogen to produce liquidhydrocarbon products and coke, a portion of which is deposited on saidcatalyst in an amount to provide between 8 and 22 wt. percent carbonthereon; and

(b) contacting the resultant coked catalyst with steam in a gasificationzone operating at temperatures between 1250 and 1500 and a pressurebetween atmospheric and 150 p.s.i.g. to produce a low methane, hydrogenrich gaseous stream.

2. The process of claim 1, wherein the catalyst support is selected fromthe group consisting of gamma alumina, bauxite and activated clay.

3. The process of claim 1, wherein said catalyst is nickel and uraniumoxides deposited on bauxite.

4. A process according to claim 1 wherein said metal oxide is manganeseoxide.

5. A process according to claim 1 wherein said metal oxide is nickeloxide.

6. A process according to claim 5 wherein uranium or thorium is alsosupported with said nickel oxide.

7. A process according to claim 5 wherein said catalyst is Ni-Th on abauxite support.

8. A continuous integrated fluid coking steam gasification process forproducing liquid hydrocarbon products and a low methane, hydrogen richgaseous stream which comprises:

(a) treating a carbonaceous material having a Conradson carbon residueof at least 5 wt. percent and a supported Group V-B, VII-B or VIII metaloxide steam gasification catalyst in a coking zone operated attemperatures between 850 and 1050" F. and pressures between atmosphericand p.s.i.g. in the absence of additional hydrogen to produce liquidhydrocarbon products and coke, a portion of which is deposited on saidcatalyst in an amount to provide between 8 and 22 wt. percent carbonthereon;

(b) contacting a portion of the resultant coked catalyst with steam in agasification zone operating at a temperature between 1250 and 1500" F.and a pressure between atmospheric and 150 p.s.i.g. to produce a lowmethane, hydrogen rich gaseous stream; and

(c) recycling said steam treated catalyst to said coking zone.

9. A process according to claim 8 wherein a portion of said cokedcatalyst is heated to a temperature of at least 1250 F., and a firstportion of said heated coked catalyst is recycled to said coking zoneand a second portion of said heated coked catalyst is treated in saidgasification zone.

10. A process according to claim 8 wherein said metal oxide is manganeseoxide.

11. A process according to claim 8 wherein said metal oxide is nickeloxide.

12. A process according to claim 8 wherein said catalyst is Ni-Th on abauxite support.

References Cited UNITED STATES PATENTS 2,513,022 6/ 1950 Helmers et al.23-212 2,546,606 3/1951 Mayland 252-373 2,888,395 5/1959 Henny 48-1973,017,250 1/ 1962 Wat-kins 23-212 2,600,430 6/1952 Riblett 208-542,885,350 5/1959 Brown et al 208-127 3,542,532 11/1970 Johnson et a1.208-127 3,179,584 4/1965 Hamner et a1 208-127 3,172,840 3/1965 Paterson208-79 FOREIGN PATENTS 541,962 12/ 1941 Great Britain 252-416 HERBERTLEVINE, Primary Examiner U.S. CL X.R.

